2016-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/648970摘要：發光二極體 (Light Emitting Diode, LED) 照明具環保節能之優勢，然 LED 是由半導體材料所製成的發光元件，而白光 LED 光譜落於 400 nm – 550 nm 區間，屬於視網膜藍光危害區，且其中尖銳的藍光波峰所呈現的單點強度長期暴露也可能對黃斑部產生累積性的負面效應，因此 LED 照明如何呈現最適合生理機轉的光學表現，有待醫學體系的專業研究並定義。 本團隊第一階段之研究結果發現若大鼠置於白光 LED或藍光 LED 750 Lux 之照度下，以12 小時亮/12 小時暗之週期照射7天後，視網膜電波圖之b wave 下降，組織切片檢查發現outer nuclear layer 細胞數目減少，穿透式電子顯微鏡檢查發現感光細胞及RPE細胞之細胞核及粒線體有形態學上的變化，TUNEL 染色法及免疫組織化學染色法則發現有感光細胞凋亡及視網膜氧化自由基增加。而大鼠若置於省電燈泡或白熾燈泡下則無以上之變化產生。此研究結果證實LED確實在平常之照度下，長期使用確實會對視網膜造成傷害。本實驗結果已於2013年被美國政府期刊Environmental Health Perspectives (impact factor 7.26) 接受刊登。本計畫乃進一步針對LED 做為室內長期照明之頻譜影響，及所誘發的視網膜危害生理機轉進行檢驗分析。透過動物實驗，以視網膜電波圖 (electroretinogram, ERG) 檢查視網膜功能上所受的影響，也以組織切片對比染色法 (H&E染色法) 以及穿透式電子顯微鏡 (transmission electron microscopy, TEM) 等，觀察感光細胞 形 貌 上 的 病 理 變 化 ， 並 透 過 TUNEL 染 色 法 及 免 疫 組 織 化 學 染 色 法 (immunohistochemistry; IHC) ，配合視網膜氧化自由基的偵測，同時藉由西方墨點法 (Western Blot) 與微陣列檢驗分析 (DNA microarray) 研究LED 照明對視網膜細胞結構的影響，乃至特定基因對神經系統或腦部活動的複合衝擊成因。 本計畫根據前期研究之結果設計動物實驗，以三原色單波長 LED 以及 LED 全頻譜光源，色溫 6500 K、暴露時間 28 天、照光強度 150 lux ~ 750 lux 等暴露參數組合進行分組實驗，觀察視網膜感光細胞產生的光化學傷害 (photochemical damage)，藉以推算頻譜組合閾值及劑量效應關係。在全球節能減碳政策的浪潮下，未來LED照明將迅速取代傳統照明光源，預期將有相關於視覺系統的影響產生，而這項暴露的風險評估必須及早進行。故本計畫研究結果可建立後續醫學研究的基礎，同時提供產業發展的重要參考。除此之外，亦可提昇使用者之防護意識，進一步促進國人的視覺健康。 <br> Abstract: Light Emitting Diode (LED) is surged by the energy conservation trend globally. However, LED is developed from an indicator rather than illuminator, as a result, there are health concerns and practical issues should be studied before further expansion of use. Blue light LED wavelength is ranged from 400 nm to 550 nm, which is the retinal hazard region. Moreover, the sharp blue peak in the spectrum signifies the strong intensity which causes blue light hazard, but hard to be recognized by human eyes. Macular degeneration is also projected with long term exposure of this type of light source. Therefore, medical study and description is critical to clarify its mechanism and dose response relationship. In our previous study, we examined the LED-induced retinal neuronal cell damage in the Sprague-Dawley rat model. Blue LEDs (460 nm) and full-spectrum white LEDs coupled with matching compact fluorescent lights were used for exposure treatments. H&E staining and the TEM study revealed apoptosis and necrosis of photoreceptors, which indicated blue-light induced photochemical injury of the retina. Free radical production in the retina increased in the LED exposure groups. The IHC stain demonstrated that oxidative stress was associated with retinal injury. The results raise questions related to adverse effects on the retina from chronic LED light exposure compared to current lamp sources that have less blue light. Our results clearly suggest a precautionary approach may be advisable with regard to the employment of blue-rich “white” LEDs for general lighting. The primary study result was accepted for publication in the journal of Environmental Health Perspectives (impact factor 7.26) in 2013. Here, we are proposing this continuous project to determine the full mechanisms of the retinal injury induced by LED light at domestic illumination level in a rat model. Developing from the pilot study, we will expand the animal study by different parameters to further confirm the blue light hazard. Full spectrum LED (CCT 6500 K) with single wavelength LED arrays (Red, Green, and Blue LEDs) will be used for experiments. In order to establish the dose dependent effect, we will also include different exposure intensities ranging from 150 lux – 750 lux under the cyclic routine (12 h-dark / 12 h-light). The experimental rats will be sacrificed and their retinal tissues will be taken for pathological analysis after 4 week of exposure. Some particular biomarkers will be investigated and identified by functional electroretinogram (ERG) and morphological approaches: H&E staining, transmission electron microscopy (TEM) followed by biochemical detections including TUNEL staining, immunohistochemistry (IHC), and free radical assay (reactive oxidative species). DNA microarray analysis will be used to identify the genes expression pattern of retina after light exposure, and will be confirmed by the Western blotting method. By performing these methods, we will determine the threshold of retinal neuronal cell damage induced by specific wavelengths or exposure intensity. LEDs are expected to become the primary domestic light sources in the near future. Light exposure experiments in the rat model provide practical evidence to evaluate the potential for light-induced retinal degeneration processes. We hope to highlight the dose response relationship and exposure threshold for major light spectrums for adapting LED as an indoor light source.LED 室內照明LED 光源節能照明視網膜感光細胞indoor LED lightingLED light sourceenergy savingretinal photoreceptor